Heretofore various devices have been used for drawing circles. However, those devices commonly used typically require the user to set the drafting device to a specific radius or diameter by first adjusting the instrument with the aid of a separate measuring device such as a ruler, then accomplishing a finer adjustment by drafting and measuring trial circles until the proper size is obtained. All manual drafting devices in common use require the same time-consuming procedures in order to draft a circle, and require a great deal of patience and attention on the part of the draftsman in order to maintain the accuracy of the circle throughout the drafting procedure. Such devices employ an integral pencil or pencil lead and/or pen either as a part of the device or clamped to the device. Such pen and particularly pencil arrangements add to the difficulty of drafting an accurate circle in a reasonably short period of time.
There are various prior art patents which employ flat sheets of plastic, etc., and holes adapted to receive the end of a pencil, for example. All such devices known to applicants have major disadvantages, for example in that it is extremely time-consuming for the user to locate which hole is to be employed. Typically, such devices are full of indicia or numbers to specify which hole is which, creating great amounts of confusion, difficulty in manufacture, difficulty in using, etc. Other defects of the prior art devices include the fact that they are conventionally relatively difficult to rotate on the paper, and/or are highly expensive.